Tubular pieces of copper or copper alloys, particularly bronze, which serve as blanks for manufacturing bushings, rings and other shaped articles suffered, up till now, from the drawback that the outer layer showed gas inclusions over a substantial depth so that the blanks had to be turned on a lathe over this depth, whereas the inner layer of these blanks were formed of a porous layer containing oxides. With the centrifugal casting methods used up till now for casting copper and copper alloys, the centrifugal ingot mold had to be filled with a relatively low speed for avoiding so-called through-holes which resulted in nonuniform charging of the mold, inaccuracies at the inner side of the casting and to nonuniform temperature stress of the mold which in turn results in increased consumption of materials and in a rapid wear of the mold.